Solid state batteries (SSB)s include solid electrodes and a solid electrolyte material. Various methods of forming SSBs have been developed. Yet, fabricating a high energy density SSB has been a challenge, for example due to high sensitivity of suitable solid electrolytes to atmospheric moisture. It has also been difficult to achieve good interfacial resistance between active material of the electrodes and the solid electrolyte particles. For example, sintering at high temperatures of about 900° C. is used to provide interfacial contact between the electrolyte and the active material, but eliminates the use of carbon as an electronic conductor due to the high temperatures.